planck-js/example/ConvexHull.js

2D JavaScript physics engine for cross-platform HTML5 game development

/*
 * MIT License
 * Copyright (c) 2019 Erin Catto
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

planck.testbed('ConvexHull', function(testbed) {
  var pl = planck, Vec2 = pl.Vec2;
  var world = new pl.World();

  testbed.x = 0;
  testbed.y = 0;

  var COUNT = 8;

  var auto = false;
  var points = [];

  var shape;

  Generate();

  function Generate() {

    var lowerBound = Vec2(-8.0, -8.0);
    var upperBound = Vec2(8.0, 8.0);

    points.length = 0;
    for (var i = 0; i < COUNT; ++i) {
      var x = 10.0 * Math.random() - 5;
      var y = 10.0 * Math.random() - 5;

      // Clamp onto a square to help create collinearities.
      // This will stress the convex hull algorithm.
      var v = Vec2.clamp(Vec2(x, y), lowerBound, upperBound);
      points.push(Vec2(x, y));
    }

    shape = pl.Polygon(points);
  }

  testbed.keydown = function(code, char) {
    switch (char) {
    case 'Z':
      auto = !auto;
      break;

    case 'X':
      Generate();
      break;
    }
  };

  testbed.info('X: Generate a new random convex hull, Z: Auto-generate');

  testbed.step = function() {
    testbed.drawPolygon(shape.m_vertices, testbed.color(0.9, 0.9, 0.9));

    for (var i = 0; i < points.length; ++i) {
      testbed.drawPoint(points[i], 3.0, testbed.color(0.3, 0.9, 0.3));
      // testbed.drawString(points[i] + Vec2(0.05, 0.05), "%d", i);
    }

    // if (shape.validate() == false) {
    //   m_textLine += 0;
    // }

    if (auto) {
      Generate();
    }
  };

  return world;
});